The present invention relates generally to electric wire harness fabricating apparatus, and more particularly, relates to an apparatus for feeding a wire or wires from a wire supply to a wire harness fabricating device.
As is well known, electrical harnesses are provided with a plurality of wires, both ends of which are attached to connectors referred to commonly as a “master” and a “slave” connector and which are used to connect electronic apparatus together by connecting two connectors thereof to the connectors of the apparatus.
The two connectors and wires are held in the wire harness by press-fitting the end portions of the wires into contact with terminals of the two and this is referred to as “pressure welding”. The master and the slave connector are formed in a rectangular shapes in a direction orthogonal to the longitudinal direction the wires. The wires are aligned in a longitudinal direction of the connector on the same line by a pitch of a unit of several millimeters and the wires are pressure-welded to the connector terminals.
Pressure welding of the wires and the connectors is carried out by known pressure welding apparatus. The wires are supplied from wire spools provided at a wire supply apparatus to the pressure welding apparatus by a predetermined length. The supply amount is normally matched to a length of the wire disposed on the outermost side of the electric harness. The wire is supplied to the pressure welding apparatus by a pair of upper and lower feed rollers which rotate and the wire utilizing frictional forces produced between the rollers and wire.
The rollers are rotated by utilizing a drive source with a servo motor. When the servo motor is rotated, the servo mechanism is operated in accordance with a rotational number thereof to thereby rotate the rollers. The amount of wire reeled from the rollers is calculated in accordance with the number of rotations of the servo motor. As is known, the servo mechanism refers to a mechanism which is made to follow automatically when input of an apparatus constituting a control object is arbitrarily changed such that an output (position, direction, angle or the like) becomes a previously set object value.
Meanwhile, the supply of the wire to the pressure welding apparatus, is based on the premise that there are no external factors of breakage of the wire insulation, variance of humidity or temperature and the like. However, in case that the wire cannot accurately be transported due to such external factors, a length of the transported wire is not converged into an allowable range and is either excessively long or excessively short. Thus, there is conceivable a case of fabricating a wire harness with wires without a consistent length and there is a concern of deteriorating yield thereby. Naturally, finished harnesses are inspected and when the harness is defective, it is discarded. However, it is preferable to be able to know whether a wire as fed to the fabricating apparatus is provided with a standard, desired length (“standard value”) before fabricating a the harness.
The present invention is directed to a fabricating apparatus that increases the yield of production of wire harnesses by determining when the wires do not match a standard value set for the harness.